414 GEOLOGY OF NORTHWESTERN TEXAS. 



Dr. Newberry stated before the International Congress of Geologists at 

 at Berlin that no Permian had been found in the United States, and gave as 

 a reason for so stating that the fossils found in the so-called Permian Beds 

 were all types of the Coal Measures. That was before the Texan field had 

 been explored to any extent. He could not now repeat the assertion, for there 

 are fossils in the Texas strata that could not with any propriety be said to be- 

 long to the Coal Measures. By reference to the list of fossils described by 

 Dr. White, given in another place, it will be seen that out of the thirty - 

 one species described fully one-half are common characteristic Coal Measure 

 species, but the other half can not with any degree of propriety be referred 

 to that series. 



Since Dr. White's article was written I have collected fossils at different 

 places at the same geologic horizon, and have found other forms both of the 

 Coal Measures and Permian. At Ben Ficklin, in Tom Green County, at the 

 extreme southern edge of the Clear Fork Beds, I found in the same stratum 

 Productus, Murchisonia, Aviculopecten, and Medlicottia. Heretofore I had not 

 found a single specimen of Productus in the Permian Beds. 



Prof. E. D. Cope has described the vertebrate fossils from the Permian 

 Beds of Texas, a list of which appears in another place in this Report. This 

 list embraces upward of fifty species collected from the same beds as those 

 from which the invertebrates were taken that were described by Dr. White, 

 some of them a little higher in the series. By reference to this list it will be 

 seen at a glance that the beds could not be referred to anything else than the 

 Permian. Of this reference Prof. Cope says: 



"The Texan genera of this group, so far as yet known, are about equally 

 related to the Ural and South African types. The age of the former deposit 

 is the Permian, which includes, according to Murchison, the Todtliegende and 

 Zechstein of Thuringia. The age of the South African Beds is uncertain, but 

 is suspected by some authors to be Triassic, and by Owen to be Paleozoic. 

 In discussing the age of the clepsydrops shales of Illinois, which had been 

 referred to the Coal Measures by all previous investigators, I left the question 

 open as to whether they should be referred to the Permian or Triassic forma- 

 tions.* The evidence now adduced is sufficient to assign the formation, as 

 represented in Illinois and Texas, to the Permian. Beside the saurian genera 

 above mentioned, the existence of the ichthyic genera Janassa, Ctenodus, and 

 Diplodus in both localities renders this course necessary." 



The following is a list of the fossils described by Dr. White, American 

 Naturalist, February, 1889, pp. 109, 128: 



♦Proceedings Philadelphia Academy, 1875, p. 405. 



